Evolution Pathway of CIGSe Nanocrystals for Solar Cell Applications

Abstract

CuIn x Ga 1−x Se 2 nanocrystals synthesized via the hot injection route have been used to make thin film solar cells with high power conversion efficiency. Thus, CuIn x Ga 1−x Se 2 nanocrystals have the potential to provide a low cost and high efficiency solution to harvest solar energy. Stoichiometry control of these nanocrystals offers the possibility of tuning the band gap of this material. It is important to understand how the composition of quaternary CuIn x Ga 1−x Se 2 nanocrystals evolves to control the stoichiometry of this compound. We report a systematic study of the growth and evolution pathways of quaternary CuIn 0.5 Ga 0.5 Se 2 nanocrystals in a hot coordination solvent. The reaction starts by the formation of a mixture of binary and ternary nanocrystals, which transforms subsequently to CuIn 0.5 Ga 0.5 Se 2 nanocrystals. These binary and ternary compounds dissolve in the course of the reaction, so as to provide the molecular precursor for monophasic CuIn 0.5 Ga 0.5 Se 2 nanocrystals to form. Here, we study the growth sequence of these spherical, monophasic CuIn 0.5 Ga 0.5 Se 2 nanocrystals as a function of time. Control experiments indicated that the phase changes of CuIn 0.5 Ga 0.5 Se 2 nanocrystals are temperature-and time-dependent. The change in the stoichiometry of CuIn 0.5 Ga 0.5 Se 2 during growth was estimated using Vegard's law.

Preparation of Cu(In,Ga)S2Absorber Layers for Thin Film Solar Cell by Annealing of Electrodeposited Cu-Ga-S Precursor Layers

“…35 Recently, Mahshid Ahmadi et al reported that the CIGSe nanocrystals formed with the binary phases of CuSe and In 2 Se 3 as the primary intermediates. 36 Thus the similar result was expected to complete the conversion to ternary chalcopyrite phase CuGaS 2 from binary compounds as the primary intermediates by increasing the annealing temperature. The formation of CuGaS 2 (CGS) is thermodynamically preferred over the formation of CuInS 2 (CIS) and it has been shown that CuGaS 2 (CGS) crystals can be even grown from an indium solution.…”

Effect of Solvent Chelating on Crystal Growth Mechanism of CZTSe Nanoink in Polyetheramine

“…Compared to other amine solvent groups, polyetheramine enhances the attack against the copper, which made the first phase unstable. This resulted in the appearance of binary phase CuSe 2 in the early stages of the reaction (at 3 hr); however, it did not appear later, which indicates that the polyetheramine-based reaction was very rapid [50]- [51]. To further investigate the valence states of four ions, XPS analysis was used to examine elements valence states of 3-hr nanoparticles, as shown in Fig.…”

Insight into the mechanism of Sb promoted Cu(In,Ga)Se2 formation

“…For our mechanism studies, we first investigated the effect of Sb on the formation of Cu-Se binary compounds, because Cu-Se phases are essential for CIGS formation [11] and evolution of Cu-Se binary phases takes place first as a result of favorable reaction kinetics [8,18,19]. We chose solvothermal process as the model method because CIGS formation pathway in solvothermal synthesis has been proved via the reaction of Cu-Se binary selenide with In and Ga precursors [18].…”

“…Mobile Cu + cations delocalize in Cu 3 SbSe 3 lattice at elevated temperature (e.g., 200 1C) and react with In and Ga precursors to form CIGS with favorable kinetics, due to facilitated mass transfer and high reactivity of Cu + cations. Here, the In and Ga precursor may be the binary selenide complexes [8,24,25] or cations of these two metals [19]. After consumption of Cu in Cu 3 SbSe 3 , the remaining Sb-Se species react with Cu 2 Se to further supply Cu 3 SbSe 3 .…”